If you are happy with your current setup and it works OK that surely there is no compulsion to "update". As long as you take care of site security. I have a previous client still using VirtueMart 3.8.8 10472 with the latest (last?) J3 version, Joomla! 3.10.12. She intends on using it until (if) something breaks.
If you are using Rocket Theme then you could be having issues with their template overrides which may need editing to suit your preferred layout. I never had success with RT in getting a good working site so stopped using them many years ago.